ifelse                 package:base                 R Documentation

_C_o_n_d_i_t_i_o_n_a_l _E_l_e_m_e_n_t _S_e_l_e_c_t_i_o_n

_D_e_s_c_r_i_p_t_i_o_n:

     'ifelse' returns a value with the same shape as 'test' which is
     filled with elements selected from either 'yes' or 'no' depending
     on whether the element of 'test' is 'TRUE' or 'FALSE'. If 'yes' or
     'no' are too short, their elements are recycled.

_U_s_a_g_e:

     ifelse(test, yes, no)

_A_r_g_u_m_e_n_t_s:

    test: a logical vector

     yes: return values for true elements of 'test'.

      no: return values for false elements of 'test'.

_R_e_f_e_r_e_n_c_e_s:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

_S_e_e _A_l_s_o:

     'if'.

_E_x_a_m_p_l_e_s:

     x <- c(6:-4)
     sqrt(x)#- gives warning
     sqrt(ifelse(x >= 0, x, NA))# no warning

     ## Note: the following also gives the warning !
     ifelse(x >= 0, sqrt(x), NA)

